1. Field of the Invention
The present invention relates to an ink cartridge that is used in the state of having been installed in an inkjet recording apparatus, and a sealing member that can be welded to an ink cartridge.
2. Description of the Related Art
In general, an ink cartridge for an inkjet recording apparatus includes an ink supply port and an air communication part. Ink can be continuously supplied by supplying the ink through the ink supply port to the recording head of the inkjet recording apparatus and by simultaneously taking the air into the ink cartridge through the air communication part. During shipping of the ink cartridge, the air communication part and the ink supply port are sealed to thereby prevent evaporation or leakage of the ink. Among various methods for sealing the air communication part, there is a method in which a sealing member having good sealing performance such as a film is welded to the casing of the ink cartridge to thereby seal the air communication part. A user of the ink cartridge opens, upon use of the ink cartridge, a portion of the sealing member that seals the air communication part to bring the inside of the ink cartridge into communication with the air.
Such a sealing member is composed of a material that contains silica, alumina, or the like; prevents evaporation of ink; and does not release an environmentally unfriendly substance even when being incinerated. Examples of such a material are described in Japanese Patent Laid-Open No. 2002-331688. Japanese Patent Laid-Open No. 2002-331688 discloses that a packaging material for an ink cartridge is formed by laminating two or more gas-barrier layers of a resin layer to which SiOx is deposited and a resin layer to which Al2O3 is deposited. Such lamination of two or more layers enhances the gas barrier property of the packaging material and suppresses evaporation of ink.
The casing of an ink cartridge needs to satisfy the following requirements to store ink therein.    1. having resistance to ink stored therein    2. not altering the composition of ink components    3. having low material cost and low manufacturing cost because ink cartridges are supply items    4. being recyclable because awareness of global environmental problems has been raised    5. having relatively low molding shrinkage    6. being composed of a material having high stiffness
An example of a casing material satisfying the above-described requirements is a resin such as modified PPO, PS, PBT, PET, or PP. Among these resins, polypropylene (PP) is suitable in view of a gas barrier property, toughness, resistance to leaching, and cost.
In recent years, environmental problems caused by discarding plastic products such as ink cartridges have received attention, and hence the recyclability of a product is becoming a significant factor to consider as with the functionality of a product. Under these circumstances, attempts to recycle materials have been made in which waste plastic members that are recyclable by appropriate treatments are collected from waste products and recycled as plastic products. For example, Japanese Patent Laid-Open No. 2000-198116 discloses an invention in which collected ink cartridges are recycled as ink cartridges. Specifically, Japanese Patent Laid-Open No. 2000-198116 discloses the following invention: recyclable thermoplastic members are collected, pulverized, and subsequently washed to provide a pulverized mixture; thermoplastic materials are separated from the pulverized mixture; and thermoplastic members equivalent to those collected are produced from the thermoplastic materials.